Extracellular matrix-derived gels, cell-growth scaffolds and related methods are described herein.
The current trend towards minimally invasive, outpatient-based surgical procedures has prompted the development of injectable scaffolds, which can be inductive and bioactive or they can be non-inductive “place holders.” Injectable scaffolds can be used in combination with endoscopic or laparoscopic techniques to deliver bioactive proteins and/or cells, or bulking agents to target tissues. Purified collagen, gelatin, autologous fat, hyaluronic acid, and synthetic materials are clinically used as injectable scaffolds in regenerative medicine for the treatment of urinary incontinence, reflux disease, and laryngeal pathologies [Lightner D J, et al. Injectable agents: present and future. Curr Urol Rep. 2002 October; 3(5):408-13; Lehman G A. Injectable and bulk-forming agents for enhancing the lower esophageal sphincter. Am J Med. 2003 Aug. 18; 115 Suppl 3A:188S-91S; Duruisseau O, et al. Endoscopic rehabilitation of vocal cord paralysis with a silicone elastomer suspension implant. Otolaryngol Head Neck Surg. 2004 September; 131(3):241-7]. In addition, purified collagen gels have been investigated in pre-clinical studies as a substrate for the delivery of neonatal cardiomyocytes to infarcted myocardium [Zhang P, et al. Artificial matrix helps neonatal cardiomyocytes restore injured myocardium in rats. Artif Organs. 2006 February; 30(2):86-93] or as an injectable scaffold for articular surface repair [Xu J W, et al. Injectable tissue-engineered cartilage with different chondrocyte sources. Plast Reconstr Surg. 2004 Apr. 15; 113(5):1361-71]. However, overly-purified, chemically modified or synthetic materials can lead to adverse immune responses by the host and limit cell migration into the matrix.
Scaffolds composed of naturally occurring extracellular matrix (ECM) possess many bioactive properties that have been shown to lead to constructive remodeling of virtually every tissue type with minimization of scar tissue formation. ECM-derived scaffolds have been used for the repair of a variety of tissues including lower urinary tract structures [Dedecker F, et al. [Small intestinal submucosa (SIS): prospects in urogenital surgery]. Prog Urol. 2005 June; 15(3):405-10; Wood J D, Simmons-Byrd A, et al. Use of a particulate extracellular matrix bioscaffold for treatment of acquired urinary incontinence in dogs. J Am Vet Med Assoc. 2005 Apr. 1; 226(7):1095-7], esophagus [Badylak S, et al. Resorbable bioscaffold for esophageal repair in a dog model. J Pediatr Surg. 2000 July; 35(7):1097-103; Badylak S F, et al. Esophageal reconstruction with ECM and muscle tissue in a dog model. J Surg Res. 2005 September; 128(1):87-97], cardiac tissue [Badylak S, et al. Extracellular matrix for myocardial repair. Heart Surg Forum. 2003; 6(2):E20-6; Badylak S F, et al. The use of extracellular matrix as an inductive scaffold for the partial replacement of functional myocardium. Cell Transplant. 2006; 15 Suppl 1:S29-40; Robinson K A, et al. Extracellular matrix scaffold for cardiac repair. Circulation. 2005 Aug. 30; 112(9 Suppl):I135-43], and musculotendinous structures [Badylak S, et al. Naturally occurring extracellular matrix as a scaffold for musculoskeletal repair. Clin Orthop Relat Res. 1999 October(367 Suppl):S333-43; Badylak S F, et al. The use of xenogeneic small intestinal submucosa as a biomaterial for Achilles tendon repair in a dog model. J Biomed Mater Res. 1995 August; 29(8):977-85; Zantop T, et al. Extracellular matrix scaffolds are repopulated, in part, by bone marrow-derived cells in a mouse model of achilles tendon reconstruction. J Orthop Res. 2006 June; 24(6):1299-309] tissues, often leading to tissue-specific constructive remodeling without scar formation.
U.S. Pat. No. 5,275,826 discloses an ECM-derived fluidized, injectable, non-immunogenic tissue graft that promotes endogenous tissue growth in the location of the injection of the tissue graft. The composition is comprised of tunica submucosa, muscularis mucosa and stratum compactum of the small intestine of a warm-blooded vertebrate.
U.S. Pat. No. 5,516,533 discloses a tissue graft composition comprised of intestinal submucosa delaminated from both the tunica muscularis (an outer layer of the intestine) and at least the luminal portion of the tunica mucosa (inner layer of the intestine).
U.S. Pat. No. 5,866,414 discloses a cell-growth composition containing protease-digested submucosal tissue, and added nutrients to support cell growth. The submucosal tissue and nutrients are combined in a solution, which is then gelled to form a solid or semi-solid matrix.
U.S. Pat. No. 6,893,666 discloses a composition and methods for using a tissue regenerative matrix to promote the restoration, remodeling or repair of connective tissue. The composition of the matrix comprises devitalized mammalian epithelial basement membrane of the intestine and tunica propria, which can further include submucosa, tunica muscularis, growth factors, a cell, or a polymer. The tissue can be obtained from the urinary bladder, skin, esophagus and small intestine.
U.S. application Ser. No. 11/182,551 discloses a composition consisting essentially of an emulsified or injectable extracellular matrix composition from a mammalian source for regeneration of absent or defective myocardium. The application also discloses a composition comprising synthetic or mammalian extracellular matrix compositions and additional components, such as a cell, peptide, drug, or nutrient. The application also discloses methods of making and using the composition. Divisional applications related to application Ser. No. 11/182,551 include: application Ser. No. 11/367,870; 11/448,351; 11/448,355; 11/448,931; and Ser. No. 11/448,968. These applications disclose a manner of polymerizing the emulsified composition by altering the pH of the composition. However, none of the applications discuss the use of temperature to regulate gelation.
Many forms of ECM scaffolds have already received regulatory approval and have been used in more than 500,000 human patients. However, these current forms of ECM are limited by the material and geometrical properties inherent to the tissue from which they are derived (such as sheets or tubes of tissue) and delivery via injection is limited to powder suspensions.